In recent years, virtualization techniques that enable virtual machines to communicate with each other have been used in a data center accommodating a plurality of customer systems so that the plurality of customer systems are separated from each other within the data center. The virtualization techniques include a L2 (Layer 2) tunneling method that allows a pair of virtual machines to be communicably coupled with each other via virtual communication lines.
In a data center, for example, a plurality of virtual machines arranged within the same customer system are communicably coupled with each other using a L2 tunneling method. In the case, actual transmission routes through which packets are exchanged among the plurality of virtual machines are determined based on a setting status of virtual communication lines that are established within the customer system so as to communicably couple any pair of virtual machines using the L2 tunneling method.
In a communication system where a plurality of virtual machines communicate with each other using a L2 tunneling method as mentioned above, it is sometimes required to capture intended packets from all the packets being transmitted among the plurality of virtual machines, for the purpose of analyzing the operational states of the plurality of virtual machines, for example, when a failure has occurred in the communication system. As a method for capturing intended packets that are flowing in a communication network, for example, a capture device may be installed at an arbitrary point along a transmission route in the communication network so as to capture the intended packet from all the packets being transmitted in the communication network.
However, the above mentioned method has a problem that intended packets may not be captured efficiently. That is, when the arrangement of the plurality of virtual machines are changed and thereby the currently-used communication routes are also changed, a plurality of capture devices need to be installed along all the relevant transmission routes before and after changing the arrangement of the plurality of virtual machines.